This invention relates to a scroll compressor for a refrigerating operation and an air-conditioning operation.
FIG. 14 is a vertical sectional view of a scroll compressor disclosed by Unexamined Japanese Utility Model Publication Hei-4-84784(U). In FIG. 14, reference numeral 1 designates a stationary scroll having a spiral section 1a formed in the lower end face, the stationary scroll 1 being connected to a frame 3 with bolts; and 2, an orbiting scroll having a spiral section 2a formed in the upper end face which is equal configuration to the spiral section 1a of the stationary scroll 1, and a hollow boss section 2b extended from the lower end surface. An orbiting bearing 2c is formed on the inner surface of the hollow boss section 2b.
Further in FIG. 14, reference numeral 5 designates a crank shaft the upper end portion of which is formed into a cylindrical crank section 5a which is eccentric from the axis. The cylindrical crank section 5a is rotatably engaged with the orbiting bearing 2c. The crank shaft 5 is made up of a main shaft section 5b and an auxiliary shaft 5c. The cylindrical surfaces of the main shaft section 5b and the auxiliary shaft section 5c are rotatably supported by a main bearing 3a formed on the frame 3 and an auxiliary bearing 4a formed on a subframe 4, respectively.
The crank shaft 5 further includes a rotor shaft section 5d, on which a rotor 6 is mounted by shrinkage fitting. The rotor 6 and a stator 7 form a motor section.
In order to balance the centrifugal force of the orbiting scroll 2, an upper balance weight 8 and a lower balance weight 9 are mounted on the crank shaft 5.
When current is applied to the stator 7, the torque is transmitted to the crank shaft 5; that is, the torque is transmitted through the crank section 5a to the orbiting scroll 2, to cause the latter 2 to perform an orbiting motion to vary the volume of the compressing chamber defined by the orbiting scroll 2 and the stationary scroll 1. That is, the compressor performs a compressing action.
The crank shaft 5 is supported by the main bearing 3a and the auxiliary bearing 4a which are provided on both sides of the rotor 6. The crank shaft 5, in turn, supports a gas load applied to the crank section 5a by the compressing action, and the centrifugal forces of the upper and lower balance weights 8 and 9. (Hereinafter, the centrifugal force of the lower balance weight 9 will be disregarded, being extremely small).
Now, the crank shaft 5 will be described in more detail. FIG. 15 shows the crank shaft 5 to which no load is applied, while FIG. 16 shows the crank shaft 5 to which a load is applied.
When the compressor is in operation, a gas compression load F.sub.N acts on the crank section 5a, a main shaft reaction force F.sub.1 from the main bearing 3a is applied to the cylindrical surface of the main shaft section 5b, and an auxiliary shaft reaction force F.sub.2 from the auxiliary bearing 4a is applied to the cylindrical surface of the auxiliary shaft 5c. That is, in the crank shaft section 5, those three forces F.sub.N, F.sub.1 and F.sub.2 are balanced with one another.
The crank shaft 5, being elastic, is bent by those three forces; that is, the crank shaft 5 is relatively greatly inclined with respect to the main bearing 3a and the auxiliary bearing 4a.
FIG. 17 shows a compressor disclosed by Unexamined Japanese Patent Publication (Kokai) Sho-64-87890, and in its specification there is an expression "--being made eccentric from each other in the bearing gap between the main bearing 3a and the main shaft 5--". However, as is seen from comparison of FIGS. 17 and 14, those compressors are completely different in structure. In the compressor shown in FIG. 17, the main bearing 3a and the auxiliary bearing 4a are arranged adjacent to each other, and rolling bearings large in radial gap are generally employed. The object of the structure is based on the fact that the main shaft is tilted as much as the radial gap as shown in FIGS. 18 and 19
On the other hand, in the compressor of FIG. 14, the rotor 6 is provided between the main bearing 3a and the auxiliary bearing 4a; that is, those bearings 3a and 4a are spaced from each other. Since the bearings 3a and 4a are not adjacent to each other, the elastic deformation of the crank shaft 5 cannot be disregarded. As described with respect to the object, the angle of relative inclination of the main shaft 5b and the main bearing 3a is large, thus raising a problem. If summarized, the compressor shown in FIGS. 14 is different from the compressor shown in FIG. 17 in the problems encountered, in structure, and in the means for solving the problems.
The conventional scroll type compressor is constructed as described above. That is, since the angle of relative inclination of the main shaft section 5b and the main bearing 3a is large, no sufficiently large load capacity is provided. Furthermore, as for the main bearing 3a , the angle of relative inclination and the magnitude of the load are both severe in allowance. Therefore, in the compressor, metal contact may occur to increase the input, advance the wearing of the shaft, and seize the shaft. Thus, the compressor is low in reliability, and suffers from a difficulty that it is large in power consumption.